2012 Spring issue of Vibrations (pdf) - Ultrasonic Industry Association

Volume 22, Issue 2
Page 3
Symposium Technical Program, Continued
medical professions, physics
laboratories, and colleges and
universities around the globe.
Technical Sessions
TIME Magazine has recognized
focused ultrasound as one of
the 50 “most inspired ideas, innovations
and revolutions” of 2011,
as detailed by the Focused Ultrasound
Surgery Foundation
Newsletter, December 2011.
Magnetic resonance imaging
guided HIFU (High Intensity
Focused Ultrasound) is already
employed in treatment of some
cancers, such as breast and
prostate cancer. Many researchers
continue effort to
improve the application of HIFU
to therapy via thermal medicine,
plans for more effective delivery
of chemotherapy, and treatments
of cardiac and vascular
disease.
Keynote speaker of the Medical
Session, Dr. Thomas J.
Matula, will focus his presentation
on Therapeutic Ultrasound
and the Contribution
of Bubbles. Ultrasound contrast
agents (microbubbles) are
being developed for many diagnostic
and therapeutic applications,
from molecular imaging
to drug and gene delivery. For
therapy, it has been shown that
microbubbles can increase vascular
permeability, but they also
generate microvascular damage
leading to rupture of blood
vessels and leakage of red blood
cells. Their research center has
designed and developed a technique
to visualize the realtime
dynamics of microbubbles
inside blood vessels
using high speed photomicrography.
Using images and
video of microbubble dynamics,
such as in Figure 1,
within vessels, this presentation
will discuss the various
potential mechanisms, showing
how microbubbles may
be able to generate
bioeffects.
Additional Medical Session
papers related to
response of biologic tissue
to ultrasound include Mayo
Clinic researchers’ work
on elasticity imaging methods
that have been used to
study tissue
mechanical properties. It is
demonstrated that
tissue elasticity changes
with disease states. Other
presentations regarding
HIFU development include
treating disease in the liver
and thermal medicine applications
under development.
Characterization of
high intensity focused fields
used in therapeutic ultrasound
will be presented by
Klaus-V. Jenderka and M.
Schultz. Klaus is visiting
from University of Applied
Sciences Merseburg, where
he has a professorship of
"Physics, Sensor and Ultrasound
Technology" this
year.
Systems
Versatile Power Company
developers will present
a new system for
medical and other ultrasonic
applications that
enables a digitally controlled
AC source to operate
over a broad range
of frequencies, overcoming
limitations of traditional
drives by resonant
circuits that must operate
over a relatively narrow
frequency range. The controller
performs both
frequency scanning and
phase tracking in realtime
and has been validated
in surgical
applications.
Horns, Horns, Horns
Some of the earliest
mathematics and physics
of wave motion came
from scientists studying
musical instruments and
Dr. Thomas J. Matula is
Director, Center for Industrial
and Medical Ultrasound and
Co-Director, Center for
Ultrasound-based Molecular
Imaging and Therapy, Applied
Physics Laboratory University
of Washington.
Figure 1. Bubbles in a Blood Vessel. Small bubbles are driven by a 1
Megahertz focused ultrasound pulse with a pressure of 7 MPa. Color
has been added to the bubbles and lumen of the actual vessel in order
to highlight the process. The first cycle is shown in Frame 1 at time
zero, and three bubbles are seen near a vessel wall. In Frame 2, at time
equal to 0.6 µs, the vessel wall distends in response to the bubbles
expanding against it. In Frame 3, at time equal to 1.8 µs, the bubbles
have collapsed. The surrounding tissue, acting like a fluid, flows into the
void left by the collapsed bubbles. This inward motion is termed invagination.
The strains felt by the invaginated tissue appear to be much
greater than during distension, signaling a potential new mechanism for
drug and gene delivery applications.